Well, let's look a little closer at your financial assumptions.
Let's say, for the sake of argument, that you could get a job for the same $125k salary in boyfriend's new city. Let's also assume that, whenever you move, it will take 3 months after you move to get that new job.(so the sooner you move, the sooner you get a new job).
Let's also assume that your living expenses will be less once you move in with boyfriend.
In this situation, you are NOT talking about an extra $50k by April. You are only talking about an extra $17k, minus the difference in living expenses between your current place and living with boyfriend.
So.....let's say you'll save $800 a month in living expenses once you move in with boyfriend. (This may or may not be true, depending on your current living sitch). if so, the benefit of staying there until April is only $17k minus $800/mo x 4mos = 17,000 - 3200= 13800. Subtract a couple extra roundtrip airfares: 13800 - 1200= 12600.
Now, that's still nothing to sneeze at. If you're drowning in debt, it would seem smart to pick up the extra. But otherwise I'd say move now IF boyfriend wants you to. (If he's not anxious to start living with you then I would reconsider the whole idea of moving to be with him. )